<?php

trait A
{
    public static $name = '静静';
    public static function demo()
    {
        echo 'A中的demo...<br>';
    }
    abstract public function tt();
}

class User
{
    use A;
    public function tt(){}
}

User::demo();
echo User::$name;

$u = new User();
$u->demo();
// echo $u->name;

echo '<hr>';

